Laser induced thermal imaging apparatus

ABSTRACT

A laser induced thermal imaging (LITI) apparatus and a method of making an electronic device using the same are disclosed. The LITI apparatus includes a chamber, a substrate support, a contact frame, and a laser source or oscillator. The LITI apparatus transfers a transferable layer from a film donor device onto a surface of an intermediate electronic device. The LITI apparatus uses a magnetic force to provide a close contact between the transferable layer and the surface of the intermediate device. The magnetic force is generated by magnetic materials formed in two components of the LITI apparatus that are spaced apart interposing transferable layer and the surface of the intermediate device. Magnets or magnetic materials are formed in the two following components of the LITI apparatus: 1) the intermediate device and the film donor device; 2) the intermediate device and the contact frame; 3) the substrate support and the film donor device; or 4) the substrate support and the contact frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and incorporates herein by reference theentire contents of the following concurrently filed applications:ORGANIC LIGHT EMITTING DISPLAY DEVICE (Atty. Docket No. SDISHN.035AUS,filed ______, application Ser. No. ______); LASER INDUCED THERMALIMAGING APPARATUS WITH CONTACT FRAME (Atty. Docket No. SDISHN.036AUS,filed ______, application Ser. No. ______); FILM DONOR DEVICE FOR LASERINDUCED THERMAL IMAGING (Atty. Docket No. SDISHN.037AUS, filed ______,application Ser. No. ______); and METHOD OF MAKING AN ORGANIC LIGHTEMITTING DISPLAY DEVICE (Atty. Docket No. SDISHN.039AUS, filed ______,application Ser. No. ______).

This application claims the benefit of Korean Patent Application Nos.10-2005-0080347, 10-2005-0080348, and 10-2005-0080349, filed on Aug. 30,2005, and Korean Patent Application Nos. 10-2005-0109814,10-2005-0109815, 10-2005-0109816, 10-2005-0109819, 10-2005-0109820,10-2005-109821, and 10-2005-0109822, filed on Nov. 16, 2005, in theKorean Intellectual Property Office, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to production of electronic devices, andmore particularly, forming organic material layers in electronic devicesusing a laser induced thermal imaging (LITI) technology.

2. Description of the Related Technology

Certain electronic devices include organic layers. For example, anorganic light emitting device (OLED) includes various organic layers.Various methods have been used to form such organic layers. For example,such methods include a deposition method, an inkjet method, and alaser-induced thermal imaging (LITI) method.

In the LITI method, a film donor device is used to provide atransferable layer. The donor device is placed on a partially fabricatedelectronic device (intermediate device) such that the transferable layercontacts a surface (receiving surface) of the intermediate device onwhich the transferable layer is to be transferred. Then, a laser beam isapplied onto selected areas of the donor device, which creates heat inthe donor device in the selected area. The heat causes delamination ofdesired portions of the transferable layer. The delaminated portions ofthe transferable layer remain on the surface of the intermediate devicewhen the donor device is removed.

A typical LITI apparatus uses suction to make and keep the transferablelayer contact the surface of the intermediate device during thisprocessing. FIG. 1 is a cross-sectional view of an LITI apparatus 100.The LITI apparatus 100 includes a chamber 110, a substrate support 120and a laser source or oscillator 130. The substrate support 120 includesan intermediate device receiving groove 121 to receive an intermediateelectronic device 140 therein and a donor device receiving groove 123 toreceive a film donor device 150 therein.

To transfer organic material portions to the intermediate device withhigh precision and with fewer defects, a close contact between thetransferable layer and the receiving surface is needed. The LITIapparatus 100 includes a suction mechanism to form such a close contact.The suction mechanism includes pipes 161 and 163 and a vacuum pump P.Suction through the pipes 161 brings and keeps the intermediate device(not shown) placed in the groove 121 down. Suction through the pipes 163brings and keeps the donor device (not shown) placed in the groove 123down and in contact with the intermediate device. To conduct thesesuctions, air or other gaseous medium is required within the chamber.

However, processes performed prior to or subsequent to the LITI processare typically carried out in a vacuum atmosphere. Thus, the LITI processusing the suction described above needs to break the vacuum between thepreceding and subsequent processes.

The discussion in this section is to provide background information ofthe related technology and does not constitute an admission of priorart.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One aspect of the invention provides an apparatus for laser inducedthermal imaging (LITI). The apparatus comprises: a laser source; and asubstrate support comprising a surface facing the laser source andconfigured to receive thereon a device to be subjected to laser inducedthermal imaging, the substrate support comprising a magnet.

The substrate support may comprise a magnetic layer comprising themagnet. The magnetic layer may further comprise a non-magnetic mass anda plurality of magnets that are incorporated in the non-magnetic mass.The magnetic layer may be arranged substantially parallel to the surfaceof the substrate support. The magnet may comprise a permanent magnet oran electromagnet. The electromagnet may be electrically connected to anexternal power source, and may be configured to be selectivelystimulated. The magnet may comprise one or more forms selected from thegroup consisting of plates, pieces, chips, rods, and particles. Thesubstrate support may further comprise a non-magnetic portion.

The apparatus may further comprise: an intermediate device comprising areceiving surface and placed on the surface of the substrate support;and a film donor device comprising a transferable film layer and placedon the receiving surface of the intermediate device. The apparatus mayfurther comprise a contact frame interposed between the laser source andthe substrate support, the contact frame being movable relative to thesubstrate support between a first position and a second position, thefirst position being a first distance from the substrate support, thesecond position being a second distance from the substrate support, thesecond distance being greater than the first distance, the contact framebeing configured to press the film donor device against the intermediatedevice about the first position, the contact frame comprising at leastone magnetic material selected from the group consisting of a permanentmagnet, an electromagnet, and a magnetically attractable material. Theintermediate device may not comprise a permanent magnet or anelectromagnet.

The intermediate device and the film donor device may be arranged suchthat the receiving surface and the transferable film layer are incontact with each other. There may be substantially no bubble betweenthe receiving surface and the transferable film layer. The film donordevice may further comprise a magnetic material selected from the groupconsisting of a permanent magnet, an electromagnet and a magneticallyattractable material.

Another aspect of the invention provides a method of making anelectronic device using the apparatus described above. The methodcomprises: placing the intermediate electronic device on the surface ofthe substrate support, the intermediate device comprising a receivingsurface facing the laser source; and placing the film donor device overthe receiving surface of the intermediate device, the film donor devicecomprising a first surface facing the laser source and a second surfacefacing the substrate support; contacting the second surface of the filmdonor device with the receiving surface of the intermediate device; andpressing the film donor device against the intermediate device.

The method may further comprise irradiating a laser beam to the filmdonor device. The method may be conducted in a vacuum atmosphere. Themagnet may comprise an electromagnet, and pressing the film donor devicemay comprise activating the electromagnet. The film donor device maycomprise a magnet or magnetically attractable material, and pressing thefilm donor device may comprise causing the magnet to magneticallyinteract with the magnet or magnetically attractable material of thefilm donor device. Pressing the film donor device may further compriseproviding a contact frame located between the film donor device and thelaser source, the contact frame comprising a magnet or magneticallyattractable material, and pressing the film donor device may comprisecausing the magnet to magnetically interact with the magnet ormagnetically attractable material of the contact frame.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and advantages of the invention will become apparent and morereadily appreciated from the following description, taken in conjunctionwith the accompanying drawings.

FIG. 1 illustrates a schematic cross-sectional view of a laser-inducedthermal imaging apparatus.

FIG. 2 illustrates a schematic cross-sectional view of a laser-inducedthermal imaging apparatus according to one embodiment of the invention.

FIG. 3 illustrates a schematic exploded perspective view of alaser-induced thermal imaging apparatus according to one embodiment ofthe invention.

FIGS. 4A and 4B illustrate schematic cross-sectional views of partiallyfabricated electronic devices according to embodiments of the invention.

FIG. 4C illustrates a schematic top plan view of a partially fabricatedelectronic device according to one embodiment of the invention.

FIG. 5A illustrates a schematic perspective view of a substrate supportaccording to one embodiment of the invention.

FIG. 5B illustrates a schematic cross-sectional view of the substratesupport of FIG. 5A, taken along the line I-I.′

FIGS. 6A-6C illustrate schematic partial cross-sectional views of donordevices according to embodiments of the invention.

FIG. 7 illustrates a schematic perspective view of a contact frameaccording to one embodiment of the invention.

FIG. 8 is a flowchart of a laser-induced thermal imaging methodaccording to one embodiment of the invention.

FIGS. 9A-9F illustrate a laser-induced thermal imaging method accordingto one embodiment of the invention.

FIGS. 10A-10D illustrate a laser-induced thermal imaging methodaccording to one embodiment of the invention.

FIG. 11 illustrates a schematic perspective view of a laser oscillatoraccording to one embodiment of the invention.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

Various embodiments of the invention will be described in detail withreference to the accompanying drawings. In the drawings, like referencenumerals indicate identical or functionally similar parts or elements.

Laser-Induced Thermal Imaging Apparatus

In embodiment, a LITI apparatus uses a magnetic force to provide a closecontact between a film donor device and an intermediate device. Unlikesuctioning in the LITI apparatus of FIG. 1, the magnetic force does notrequire air or fluid within the chamber. In embodiments, contacting thefilm donor device and intermediate device using the magnetic force canbe performed either in vacuum or non-vacuum.

FIG. 2 illustrates a LITI apparatus 200 in accordance with oneembodiment. The illustrated LITI apparatus includes a chamber 210, asubstrate support 260, a contact frame 230, and a laser source oroscillator 220. The chamber 210 provides a space for processing anintermediate (or partially fabricated) electronic device 250 with a filmdonor device 241. The substrate support 260 is configured to support theintermediate device 250 and the film donor device 241. The contact frame230 is movably connected to the chamber 210 for providing a weightdownward over the film donor device 241. In certain embodiments, thecontact frame 230 may be omitted. The film donor device 241 includes atransferable layer (not shown). The transferable layer will betransferred onto the intermediate device by a laser. The laseroscillator 220 is positioned over the contact frame 230. The laseroscillator 220 is configured to irradiate a laser onto the film donordevice 241 through the contact frame 230.

In one embodiment, the LITI apparatus 200 operates as follows. First,the intermediate device 250 is introduced into the chamber 210 and isplaced onto the substrate support 260. Then, the film donor device 241is placed over the intermediate device 250. The film donor device 241comes at least partially in contact with the intermediate device 250.The film donor device 241 is pressed against the intermediate device250, using a magnetic force. During this step, the transferable layer isclosely contacted with the intermediate device. The laser oscillator 220is activated to irradiate a laser onto the film donor device 241. Then,the transferable layer is transferred from the film donor device 241 tothe intermediate device 250.

FIG. 3 illustrates a schematic exploded view of the LITI apparatus 200.The chamber 210 is shown in dotted lines. In the illustrated embodiment,the laser oscillator 220, the contact frame 230 and the substratesupport 260 are vertically aligned with one another. During the LITIprocess, an intermediate device 250 is placed on the substrate support260, and a film donor device 241 is placed over the intermediate device250. In another embodiment, the foregoing components may have adifferent arrangement, for example, a reversed configuration. In someembodiments, the substrate support may be configured to hold theintermediate device from the top. Such a substrate support may bereferred to as a substrate holder.

The chamber 210 provides a reaction space for the LITI process. Thechamber may be any suitable enclosed space in which the LITI process canbe carried out. The chamber 210 houses the contact frame 230 and thesubstrate support 260. The chamber also includes a door for introducingor removing the intermediate device 250 and the film donor device 241.In one embodiment, the chamber 210 may be configured to provide a vacuumatmosphere.

In the illustrated embodiment, the laser oscillator 220 is positioned atthe top central portion of the chamber 210 over the contact frame 230although not limited thereto. The laser oscillator 220 is configured toirradiate a laser beam onto the film donor device 241. FIG. 11illustrates one embodiment of the laser oscillator 220. The illustratedlaser oscillator 220 may be a CW ND:YAG laser (1604 nm). The laseroscillator 220 has two galvanometer scanners 221, 222. The laseroscillator 220 also has a scan lens 223 and a cylinder lens 224. Askilled artisan will appreciate that various types of laser oscillatorscan be adapted to provide a laser for the film donor device.

In the illustrated embodiment, the contact frame 230 is positioned overthe substrate support 260 although not limited thereto. The contactframe 230 is movably connected via a transmission unit 231 to the topcentral portion of the chamber 210. The contract frame 230 has a contactplate 232 configured to provide a weight over the film donor device 241.The contact plate 232 is patterned to expose portions of the underlyingfilm donor device 241 while blocking other portions. To expose theportions of the film donor device 241, the contact plate 232 includes aplurality of openings 233. The openings 233 allow the laser beam to bedirected to the portions of the film donor device 241. Thisconfiguration allows to transfer portions of the transferable layer ontothe intermediate device 250 as will be described later in detail. Incertain embodiments, the LITI apparatus may have no contact frame.

In the illustrated embodiment, the substrate support 260 is positionedat the bottom of the reaction chamber 210 although not limited thereto.The illustrated substrate support 260 has a recess 263 to accommodatethe intermediate device 250. The substrate support 260 also supports thefilm donor device 241. In addition, the substrate support 260accommodates a substrate lifter 265 and a film donor device lifter 266underneath. The substrate support 260 has through-holes 261 and 262through which the substrate lifter 265 and the film donor device lifter266 move in a vertical direction.

The intermediate device 250 is placed on the substrate support 260during the LITI process. The term, “intermediate device” refers to anydevices having a surface to form an organic material using the LITIprocess. Typically, such devices are partially fabricated electronicdevice. In one embodiment, the intermediate device 250 is a partiallyfabricated organic light emitting device. The intermediate device 250includes a surface onto which the transferable layer is to betransferred.

The film donor device 241 is placed over the intermediate device 250during the LITI process. In one embodiment, the film donor device 241includes a base substrate, a light-to-heat conversion layer, and atransferable layer, which will be further described later. Theillustrated film donor device 241 also includes a film donor device tray240 surrounding the film donor device 241. The film donor device tray240 serves as a frame for maintaining the shape of the film donor device241. The transferable layer is arranged to face the surface of the interlayer during LITI processing.

The LITI apparatus 200 of FIG. 3 uses a magnetic force to provide aclose contact between the film donor device 241 and the intermediatedevice 250. The magnetic force holds the devices 241 and 250 in closecontact, substantially free of air gaps or bubbles from between thedevices 241 and 250.

In one embodiment, the magnetic force may be generated by two or moremagnetic materials spaced apart. In embodiments, magnetic materials areformed in two components of the LITI system that are spaced apartinterposing transferable layer and the surface on which the transferablelayer is to be transferred, i.e., one positioned over the transferablelayer and the other positioned under the surface. Here, the term“components” refer to parts and devices used in the LITI process, whichinclude the intermediate device 250, the film donor device 241, thecontact frame 230 and the substrate support 260. In embodiments, magnetsor magnetic materials are formed in the two following components of theLITI system, but not limited to: 1) the intermediate device 250 and thefilm donor device 241; 2) the intermediate device 250 and the contactframe 230; 3) the substrate support 260 and the film donor device 241;or 4) the substrate support 260 and the contact frame 230.

Optionally, the magnetic materials may be provided in one of thefollowing combinations of components of the LITI system: 5) thesubstrate support 260, the intermediate device 250, and the contactframe 230; 6) the substrate support 260, the intermediate device 250,and the film donor device 241; 7) the substrate support 260, the filmdonor device 241, and the contact frame 230; or 8) the intermediatedevice 250, the film donor device 241, and the contact frame 230. In yetanother embodiment, the magnetic material may be provided in 9) thesubstrate support 260, the intermediate device 250, the film donordevice 241, and the contact frame 230. A skilled artisan will appreciatethat the magnetic material may be provided in certain other components,depending on the design of a LITI apparatus.

The magnetic materials in the pair of components are configured toattract each other such that the film donor device 241 and theintermediate device 250 form a close contact between the transferablelayer and the surface on which the layer is to be transferred. The term,“magnetic material,” as used herein, refers to either a magnet or amagnetically attractive material. A “magnet” may generally refer to apermanent or electromagnet unless otherwise indicated. The term,“magnetically attractable material,” as used herein, refers to amaterial which is not a magnet, but can be attracted by a magnet. Insome embodiments, one of the two LITI components may include a magnetwhereas the other may include a magnetically attractable material thatis not a magnet. In other embodiments, both of the two LTIT componentsmay include magnets. In certain embodiments, components including amagnet may also contain a magnetically attractable material. In all theembodiments, the components include the magnetic materials in an amountto generate a sufficient magnetic force to provide a close contactbetween the film donor device 241 and the intermediate device 250.

The magnetic force can be created in a vacuum atmosphere unlike suction.Thus, in some embodiments, the LITI process may be performed in vacuumusing the magnetically induced contact between the film donor device 241and the intermediate device 250 without breaking the vacuum. Further, inother embodiments, the magnetic force system may also be used togetherwith the suction system to improve the LITI process. The positions andconfigurations of the magnet or magnetically attractable material ineach component will be described below in detail.

In one embodiment, the magnetic material below the transferable layer ispositioned in the intermediate device 250. FIGS. 4A and 4B illustratecross-sectional views of embodiments of the intermediate devices 400Aand 400B. The illustrated intermediate devices 400A and 400B arepartially fabricated organic light emitting devices (OLEDs). Each of theintermediate devices 400A and 400B includes a substrate 401, a bufferlayer 402, a thin film transistor 440, a passivation layer 409, anelectrode 420 and a pixel partitioning walls 430. The thin filmtransistor 440 includes insulating layers 403, 404, a semiconductorlayer 405, a source electrode 406, a drain electrode 407 and a gateelectrode 408. The pixel partitioning walls 430 are formed over thepassivation layer 409 and portions of the electrode 420, exposing asubstantial portion of a top surface of the electrode 420. The electrode420 will serve as a cathode or anode of an organic light emitting diode.The transferable layer will be formed over the exposed top surface ofthe electrode 420.

In FIG. 4A, a magnetic layer 410 a is attached to the bottom surface ofthe substrate 401. In another embodiment shown in FIG. 4B, a magneticlayer 410 b is positioned between the substrate 401 and the buffer layer402. The magnetic layers 410 a, 410 b include a magnetic material whichwill be described below in detail. In one embodiment, the magnetic layer410 a or 410 b has a thickness between about 5,000 Å and about 10000 Å.

In certain embodiments, the intermediate device may include magneticmaterials embedded in any components under the electrode 420, forexample, the substrate 401, the buffer layer 402, the insulating layers403, 404, and/or the passivation layer 409, depending on the design ofthe device. In any case, the intermediate device includes the magneticmaterial in an amount sufficient to make a close contact between thefilm donor device layer and the intermediate device.

In yet another embodiment, the intermediate device may include magneticmaterial strips in certain regions of the intermediate device. FIG. 4Cillustrates a top plan view of one embodiment of an intermediate device400C. The illustrated device is a partially fabricated organic lightemitting device 400C. The device 400C includes a display region 460, adata driver 430, a scan driver 440, and power source connectors 415 and420. The display region 460 includes a plurality of pixels 470 in amatrix form. The illustrated device 400C includes magnetic materialstrips 450 a and 450 b. In the illustrated embodiment, the strips 450 aare positioned in peripheral regions outside the display region 460. Inaddition, the strips 450 b are formed in the display region 460. Theillustrated strips 450 b are substantially in parallel to one another.In other embodiments, the strips of the magnetic materials are formed inthe pixel region, but not in the peripheral regions. A skilled artisanwill appreciate that various other configurations of strips can be usedto provide a magnetic force.

In one embodiment, the magnetic material may be a magnet including apermanent magnet or an electromagnet. The permanent magnet may be alnicomagnet, ferrite magnet, rare-earth magnet, rubber magnet or plasticmagnet. The permanent magnet may take at least one form selected fromplates, pieces, chips, rods and particles. In one embodiment, thepermanent magnet may be nanometer scale magnetic particles, plates,pieces, chips or rods. Such nano-scale particles may be deposited on asurface of a component of the intermediate device, using spin coating,e-beam deposition, or inkjet deposition. In other embodiments, theplates, pieces, chips, rods and particles can be greater than nano-scalesizes.

The permanent magnet may be substantially uniformly distributed in themagnetic layer 410 a or 410 b. In another embodiment, the magnetic layer410 a or 410 b may have permanent magnet portions only in regions overwhich the transferable layer is to be transferred. In yet anotherembodiment, the magnetic layer may be a single plate formed of apermanent magnet.

In another embodiment, the magnetic material may be an electromagnet.The electromagnet may have at least one form selected from a solenoidand a toroid. A solenoid refers to a coil forming a shape of a straighttube. A toroid refers to a coil forming a shape of a doughnut.Typically, a toroid is a solenoid that is bent so that the ends meet. Insome embodiments, a solenoid or toroid may include a core ofparamagnetic or ferromagnetic material (for example, iron) inside thecoil. Because an electromagnet requires an electric current to bemagnetized, the electromagnet is connected to an external power sourcethrough a conductive line. In one embodiment, a non-display region ofthe intermediate device may include one or more electrodes electricallyconnected to designated for the electromagnet. The electrode(s) isconfigured to receive power from an external power source. In addition,the electrode(s) is connected to the electromagnet through theconductive line(s). In embodiments, the electrode(s) may be formed on anexternal surface of the device or body where the electromagnet isincorporated so as to make electrical connection to the external powersource. In other embodiments, the electrode(s) may protrude outside thedevice or body where the electromagnet is incorporated. In a finishedelectronic device formed from the intermediate device, the electrode(s)may be inactive and buried in a dielectric material. Similar to thepermanent magnet, the electromagnet may be either substantiallyuniformly or non-uniformly distributed, depending on the design of theintermediate device.

In yet another embodiment, the magnetic material may be a magneticallyattractable material while not being a magnet. Examples of themagnetically attractable material include, but are not limited to, Fe,Ni, Cr, Fe₂O₃, Fe₃O₄, CoFe₂O₄, MnFeO₄, their alloys, and a mixture oftwo or more of the foregoing materials. Other examples of themagnetically attractable material may also include plastic and ceramicmagnetic materials. Similar to the permanent magnet, the magneticallyattractable material may be in at least one form selected from plates,pieces, chips, rods, and particles. These may be nanometer-sizedparticles or greater. The magnetically attractable material may beuniformly distributed in the magnetic layer 410. In another embodiment,the magnetic layer 410 may have magnetically attractable materialportions only in regions over which the transferable layer is to betransferred. In yet another embodiment, the magnetic layer may be asingle plate formed of the magnetically attractable material.

In another embodiment, the magnetic material below the transferablelayer may be positioned in the substrate support. FIGS. 5A and 5Billustrate one embodiment of the substrate support 260 including themagnetic material. The illustrated substrate support 260 includeselectromagnets 264 in a region 263 (denoted in dotted lines) under arecess to accommodate the intermediate device. The illustratedelectromagnets 264 are aligned in a vertical direction. Theelectromagnets, however, may be arranged in various otherconfigurations, depending on the design of the substrate support. Theelectromagnets may also have various shapes and configurations asdescribed above with respect to the intermediate device. In certainembodiments, the magnetic material may be a permanent magnet ormagnetically attractable material as described above with respect to theintermediate device.

In one embodiment, the magnetic material over the transferable layer maybe positioned in the film donor device. FIGS. 6A-6C are partialcross-sectional views of film donor devices 600A-600C in accordance withembodiments. Each of the film donor devices 600A-600C includes a basesubstrate 601, a light-to-heat conversion layer 602 overlying the basesubstrate 601, an inter layer 603 overlying the light-to-heat conversionlayer 602, and a transferable layer 604 overlying the inter layer 603.Optionally, the film donor devices may include a buffer layer (notshown) between inter layer 603 and the transferable layer 604.

The base substrate 601 serves to provide the film donor device with afilm structure. The base substrate 601 may be made of a transparentpolymer. Examples of the transparent polymer include, but are notlimited to, polyethylene, polyester, teleptalrate, polyacryl, polyepoxy,polyethylene, and polystyrene. The base substrate 601 has a thicknessbetween about 10 μm and about 500 μm, optionally about 100 μm and about400 μm.

The light-to-heat conversion layer 602 is configured to absorb laser andconvert it to heat. The conversion layer 602 includes a light-absorbingmaterial. The light-absorbing material may have an optical density ofabout 0.1 to about 0.4. The light-absorbing material may include ametal, a metal oxide, and/or an organic material. Examples of themetal/metal oxide include, but are not limited to, aluminum, silver,chromium, tungsten, tin, nickel, titanium, cobalt, zinc, gold, copper,tungsten, molybdenum, lead and oxides of the foregoing. The organicmaterial may include a photosynthetic material. Examples of the organicmaterial include polymers made from a (meth)acrylate monomer oroligomer, such as an acryl (metha)acrylate oligomer, an ester(metha)acrylate oligomer, an epoxy (metha)acrylate oligomer, an urethane(metha)acrylate oligomer, etc., or mixtures of two or more of theforegoing. In addition, the conversion layer 602 may also include otheradditives such as carbon black, graphite or infrared dye.

The thickness of the light-heat converting layer 602 may vary, dependingon the light-absorbing materials and the fabrication methods. Forexample, the conversion layer may have a thickness of about 100 to about5000 Å when using a vacuum deposition method, a laser beam depositionmethod, or sputtering. In another embodiment, the conversion layer mayhave a thickness of about 0.1 to about 2 μm when using an extrusioncoating method, a gravure coating method, a spin coating method and aknife coating method.

The inter layer 603 functions to protect the light-to-heat conversionlayer 603. In one embodiment, the inter layer 603 has a high heatresistance. The inter layer 603 may be made of organic or inorganicmaterials such as polyimide polymers. The inter layer 603 has athickness between about 1 μm and about 1.5 μm. In certain embodiments,the intermediate device may be omitted.

The transferable layer 604 is a layer which will be transferred onto theintermediate device. The transferable layer 604 may be formed of anorganic material. In one embodiment where the electronic device is anorganic light emitting device, the material can be an organic lightemitting material. However, the material can also be other organicmaterials used for forming other organic elements of the organic lightemitting device. Such other elements include, but are not limited to, ahole injection layer (HIL), a hole transport layer (HTL), an electroninjection layer (EIL), and an electron transport layer (ETL). In otherelectronic devices, any material suitable for forming a target componentmay be used as the material for the transferable layer. The transferablelayer 604 has a thickness between about 200 Å and about 1,000 Å. Thetransferable layer 604 may be formed, using any suitable method, forexample, extrusion coating, gravure coating, spin coating, knifecoating, vacuum deposition, or chemical vapor deposition (CVD).

The buffer layer (not shown) serves to improve transfer properties ofthe transferable layer 604. The buffer layer may include one or more ofmetal oxides, metal sulfides, non-metal inorganic compounds, and organicmaterials. Examples of the inorganic compounds include Al and Au.Examples of the organic materials include polyimide polymers.

Referring to FIG. 6A, the light-to-heat conversion layer 602 includes amagnetic material. For example, the light-to-heat conversion layer 602may include a permanent magnet and/or electromagnet. In otherembodiments, the conversion layer 602 may include a magneticallyattractive material. The magnetic material may have variousconfigurations as described above with respect to the intermediatedevice. In other embodiments, the magnetic material may be embedded inthe base substrate 601 or the inter layer 603. In certain embodiments,the magnetic material may be embedded in at least two of the basesubstrate 601, the light-to-heat conversion layer 602, and the interlayer 603. In other embodiments, the magnetic material may be embeddedonly in certain portions of one or more of the layers 601-603, notthroughout the entire layers. For example, one or more of the layers601-603 may include the magnetic materials only under portions of thetransferable layer which will be transferred to the intermediate device.

Referring to FIGS. 6B and 6C, the film donor devices 600B and 600Cinclude a magnetic layer 605. The magnetic layer 605 includes a magneticmaterial such as a permanent magnet, electromagnet, and/or magneticallyattractable material. The magnetic material may have variousconfigurations as described above with respect to the intermediatedevice.

In FIG. 6B, the film donor device 600B includes the magnetic layer 605between the base substrate 601 and the light-to-heat conversion layer602. In FIG. 6C, the film donor device 600C includes the magnetic layer605 between the light-to-heat conversion layer 602 and the inter layer603. In another embodiment, the film donor device may include themagnetic layer interposed between the inter layer 603 and thetransferable layer 604. In yet another embodiment, the film donor devicemay include the magnetic layer on a bottom surface of the base substrate601, which faces away from the light-to-heat conversion layer 602. Incertain embodiments, the film donor device may have two or more magneticlayers interposed between two consecutive ones of the layers 601-604. Insuch embodiments, a magnetic material may further be embedded in atleast one of the base substrate 601, the light-to-heat conversion layer602 and the inter layer 603. A skilled artisan will appreciate that theconfiguration and combination of the magnetic layers can be varieddepending on the design of the film donor device.

In another embodiment, the magnetic material over the transferable layermay be positioned in the contact frame. FIG. 7 illustrates oneembodiment of the contact frame 230. The illustrated contact frame 230includes a magnetic material embedded in the frame. The magneticmaterial may be a permanent magnet or electromagnet, as described abovewith respect to the intermediate device. In another embodiment, themagnetic material may be a magnetically attractable material, asdescribed above.

In certain embodiments, the contact frame 230 may include a separatemagnetic layer. The magnetic layer includes a magnetic material asdescribed above with respect to the intermediate device. The magneticlayer can be attached on at least one of top and bottom surfaces of thecontact frame 230. In another embodiment, the magnetic layer may beembedded in the contact frame 230. In such embodiments, the layer ispatterned to have openings corresponding to the openings of the contactframe. The openings of the contact frame and the layer allow the laserbeam to be directed onto portions of the film donor device 241. Thisconfiguration allows selective transfer of the transferable film ontothe intermediate device 250. In another embodiment, the contact frameitself may be formed of the magnetic material. In all of the foregoingembodiments, the contact frame includes the magnetic material in anamount sufficient to provide a magnetic force to press the film donordevice against the intermediate device.

Laser-Induced Thermal Imaging Process

The laser-induced thermal imaging (LITI) process according toembodiments employs a magnetic force to provide a close contact betweena film donor device and an intermediate device. FIG. 8 is a flowchartillustrating one embodiment of the LITI process.

First, in step 810, an intermediate device 250 is placed on a substratesupport 260. During this step, the intermediate device 250 is moved byany suitable moving mechanism, for example, a robotic mechanism. Next,in step 820, a film donor device 241 is placed over the intermediatedevice 250. First, the film donor device 241 is vertically aligned withthe intermediate device 250 with its transferable layer facing down.Then, the film donor device 241 is moved downward onto the intermediatedevice 250. At least a portion of the transferable layer is contactedwith the intermediate device 250. Similar to the step 810, the filmdonor device 241 may be moved by the moving mechanism.

In step 830, a magnetic force is provided to pressure the film donordevice 241 against the intermediate device 250. The magnetic force maybe generated by magnetic materials positioned in two of the LITIcomponents as described above: one over the transferable layer and theother under the surface on which the layer is to be transferred. In someembodiments, one of the two LITI components may include a magnet whereasthe other may include a magnetically attractable material that is not amagnet. In other embodiments, both of the two LTIT components mayinclude magnets. The magnet may include a permanent magnet and/orelectromagnet. In one embodiment where the magnet includes anelectromagnet, the magnetic force may be time-selectively produceddepending on the needs of the LITI process. In certain embodiments,components including a magnet may also contain a magneticallyattractable material.

At this step, the magnetic force makes the film donor device 241 pushedagainst the intermediate device 250, which makes the transferable layerto more closely contact the surface on which the layer is to betransferred. In this process, all or at least some of air gaps orbubbles from between the film donor device 241 and the intermediatedevice 250 may be removed. This step facilitates a transfer of thetransferable layer onto the intermediate device 250.

In step 840, a laser is irradiated onto the film donor device 241. Thelaser provides thermal energy required to transfer the transferablelayer onto the intermediate device 250. In this step, a laser oscillator220 is activated to irradiate a laser onto a top surface of the filmdonor device 241. In one embodiment employing a contact frame 230 withopenings, the laser passes through the openings, and reaches the topsurface of the film donor device 241. During this process, the laser isdirected to selected areas of the film donor device 241. The laserreaches the light-to-heat conversion layer of the film donor device 241through the base substrate. The light-to-heat conversion layer convertsthe light energy into thermal energy, generating heat. The heat istransferred to selected portions of the transferable layer. With thisprocess, the portions of the transferable layer are released from thefilm donor device 241 and transferred to the intermediate device 250. Inanother embodiment where no contact frame is used, laser is selectivelyirradiated onto certain portions of the top surface of the film donordevice 241.

Subsequently, in step 850, the film donor device 241 is removed fromover the intermediate device 250, leaving portions of the transferablelayer on the top surface of the intermediate device 250. The film donordevice 241 may be removed using the same moving mechanism as that usedin the step 820.

Referring to FIGS. 9A-9F, an intermediate device 250 is introduced intoa transfer chamber 900. The intermediate device 250 is placed on anend-effector 910 of an robot arm 920 in the transfer chamber 900.Subsequently, the intermediate device 250 is transported into a LITIchamber 210, as shown in FIG. 9B. Then, the intermediate device 250 isplaced on a substrate support 260, as shown in FIG. 9C.

Next, a film donor device 241 is placed on the end effector 910, asshown in FIG. 9C. Subsequently, the film donor device 241 is introducedinto the LITI chamber 210, as shown in FIG. 9D. The film donor device241 is vertically aligned with the intermediate device 250. Then, thefilm donor device 241 is moved down onto the intermediate device 250, asshown in FIG. 9E. The end-effector 910 is then retrieved from the LITIchamber 210. Subsequently, a gate valve 930 is shut to provide a closedreaction chamber. In one embodiment, a vacuum atmosphere may bemaintained throughout the transfer chamber and the LITI chamber duringthese steps.

Optionally, a contact frame may be provided over the film donor device.In FIG. 9F, the contact frame 230 is moved down over the film donordevice 241. The contact frame 230 provides a weight over the film donordevice 241. The contact frame 230 may facilitate making a close contactbetween the film donor device 241 and the intermediate device 250. Inother embodiments, the contact frame may be omitted.

Next, a magnetic force is provided to make a close contact between theintermediate device and the film donor device. The magnetic force may begenerated by magnetic materials positioned in two of the LITI apparatuscomponents: one below the transferable layer and the other over thetransferable layer as described above. A skilled artisan will appreciatethat the magnetic material may be provided in certain other components,depending on the design of a LITI apparatus. In all of the foregoingembodiments, the magnetic force is exerted between the intermediatedevice and the film donor device in a sufficient strength to make acontact without air gaps or bubbles therebetween. Details of themagnetic material positions and configurations are as described abovewith respect to the LITI apparatus.

FIGS. 10A-10D are cross-sectional views illustrating how a transferablelayer is transferred onto an intermediate device. The illustratedintermediate device is a partially fabricated organic light emittingdevice 400. In the illustrated embodiment, magnetic materials arepositioned in the intermediate device and the film donor device. Inother embodiments, the magnetic materials may be provided in othercomponents of the LITI apparatus as described above.

Referring to 10A, an intermediate device 400 includes a thin filmtransistor (TFT) structure 411, a magnetic layer 410, an electrode 420,and a pixel partitioning layer 430. A portion 412 of the electrode 420is exposed through the pixel partitioning layer 430. An organic layerwill be formed on the exposed portion 412 as will be better understoodfrom later descriptions.

Next, as shown in FIG. 10B, a film donor device 600 is placed over theintermediate device 400. The film donor device 600 includes a basesubstrate 601, a magnetic layer 605, a light-to-heat conversion layer602, an inter layer 603, and a transferable layer 604 as described abovewith respect to FIG. 6B. The transferable layer 604 is at leastpartially in contact with a top surface of the pixel partitioning layer430, as shown in FIG. 10B. During this step, a magnetic force is exertedbetween the film donor device 600 and the intermediate device 400.

Then, laser is irradiated onto a selected portion of the film donordevice 600. The selected portion is positioned over the exposed portion412 of the electrode 420. The laser passes through the base substrateand the magnetic layer 605, and reaches the light-to-heat conversionlayer 602. The light-to-heat conversion layer 602 converts the lightenergy into thermal energy, generating heat. The heat is transferred tothe transferable layer 604 via the inter layer 603.

Then, upon receiving the heat, a portion of the transferable layer 604is delaminated from the film donor device 600 and comes in contact withthe exposed portion 412 of the electrode 420, as shown in FIG. 10C. Inthe illustrated embodiment, portions of the conversion layer 602, theinter layer 603 and the transferable layer 604 are separated from themagnetic layer 605. In other embodiments, only the transferable layer604 may be separated from the film donor device 600.

Subsequently, as shown in FIG. 10D, the film donor device 600 is removedfrom over the intermediate device 400. After this step, only a portion604 a of the transferable layer remains on the intermediate device 400.

In the embodiments described above, a magnetic force is used to providea close contact between the film donor device and the intermediatedevice. This configuration, unlike suctioning, does not need airpressure in the LITI chamber. Therefore, the LITI process can beperformed in a vacuum atmosphere. Since processes performed prior to orsubsequent to the LITI process are typically also carried out in avacuum atmosphere, the LITI process can be performed without breakingvacuum throughout the processes. The vacuum atmosphere may be maintainedfrom the process of depositing the hole injection layer (HIL) to theprocess of depositing the second electrode layer. (cathode layer) Inaddition, the LITI process reduces occurrence of impurities or gapsbetween the donor film and the intermediate device. This improves alifetime, yield, and reliability of the resulting electronic device.

Although various embodiments of the present invention have been shownand described, it will be appreciated by those technologists in the artthat changes might be made in these embodiments without departing fromthe principles and spirit of the invention, the scope of which isdefined in the claims and their equivalents.

1. An apparatus for laser induced thermal imaging (LITI), the apparatus comprising: a laser source; and a substrate support comprising a surface facing the laser source and configured to receive thereon a device to be subjected to laser induced thermal imaging, the substrate support comprising a magnet.
 2. The apparatus of claim 1, wherein the substrate support comprises a magnetic layer comprising the magnet.
 3. The apparatus of claim 2, wherein the magnetic layer further comprises a non-magnetic mass and a plurality of magnets that are incorporated in the non-magnetic mass.
 4. The apparatus of claim 2, wherein the magnetic layer is arranged substantially parallel to the surface of the substrate support.
 5. The apparatus of claim 1, wherein the magnet comprises a permanent magnet or an electromagnet.
 6. The apparatus of claim 5, wherein the electromagnet is electrically connected to an external power source, and is configured to be selectively stimulated.
 7. The apparatus of claim 1, wherein the magnet comprises one or more forms selected from the group consisting of plates, pieces, chips, rods, and particles.
 8. The apparatus of claim 1, wherein the substrate support further comprises a non-magnetic portion.
 9. The apparatus of claim 1, further comprising: an intermediate device comprising a receiving surface and placed on the surface of the substrate support; and a film donor device comprising a transferable film layer and placed on the receiving surface of the intermediate device.
 10. The apparatus of claim 9, further comprising a contact frame interposed between the laser source and the substrate support, the contact frame being movable relative to the substrate support between a first position and a second position, the first position being a first distance from the substrate support, the second position being a second distance from the substrate support, the second distance being greater than the first distance, the contact frame being configured to press the film donor device against the intermediate device about the first position, the contact frame comprising at least one magnetic material selected from the group consisting of a permanent magnet, an electromagnet, and a magnetically attractable material.
 11. The apparatus of claim 10, wherein the intermediate device does not comprise a permanent magnet or an electromagnet.
 12. The apparatus of claim 9, wherein the intermediate device and the film donor device are arranged such that the receiving surface and the transferable film layer are in contact with each other.
 13. The apparatus of claim 12, wherein there is substantially no bubble between the receiving surface and the transferable film layer.
 14. The apparatus of claim 9, wherein the film donor device further comprises a magnetic material selected from the group consisting of a permanent magnet, an electromagnet and a magnetically attractable material.
 15. A method of making an electronic device using the apparatus of claim 9, the method comprising: placing the intermediate electronic device on the surface of the substrate support, the intermediate device comprising a receiving surface facing the laser source; and placing the film donor device over the receiving surface of the intermediate device, the film donor device comprising a first surface facing the laser source and a second surface facing the substrate support; contacting the second surface of the film donor device with the receiving surface of the intermediate device; and pressing the film donor device against the intermediate device.
 16. The method of claim 15, further comprising irradiating a laser beam to the film donor device.
 17. The method of claim 15, wherein the method is conducted in a vacuum atmosphere.
 18. The method of claim 15, wherein the magnet comprises an electromagnet, and wherein pressing the film donor device comprises activating the electromagnet.
 19. The method of claim 15, wherein the film donor device comprises a magnet or magnetically attractable material, and wherein pressing the film donor device comprises causing the magnet to magnetically interact with the magnet or magnetically attractable material of the film donor device.
 20. The method of claim 19, wherein pressing the film donor device further comprises providing a contact frame located between the film donor device and the laser source, the contact frame comprising a magnet or magnetically attractable material, and wherein pressing the film donor device comprises causing the magnet to magnetically interact with the magnet or magnetically attractable material of the contact frame. 